The Experts below are selected from a list of 297 Experts worldwide ranked by ideXlab platform
Friedrich Gruttmann - One of the best experts on this subject based on the ideXlab platform.
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finite element analysis of saint venant torsion problem with Exact Integration of the elastic plastic constitutive equations
Computer Methods in Applied Mechanics and Engineering, 2001Co-Authors: Werner Wagner, Friedrich GruttmannAbstract:Abstract In this paper torsion of prismatic bars considering elastic–plastic material behaviour is studied. Based on the presented variational formulation associated isoparametric finite elements are developed. The unknown warping function is approximated using an isoparametric concept. The elastic–plastic stresses are obtained by an Exact Integration of the rate equations. Thus the ultimate torque can be calculated in one single load step. This quantity describes the plastic reserve of a bar subjected to torsion. Furthermore, for linear isotropic hardening no local iterations are necessary to compute the stresses at the Integration points. The numerical results are in very good agreement with available analytical solutions for simple geometric shapes. The arbitrary shaped domains may be simply or multiple connected.
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Finite element analysis of Saint–Venant torsion problem with Exact Integration of the elastic–plastic constitutive equations
Computer Methods in Applied Mechanics and Engineering, 2001Co-Authors: Werner Wagner, Friedrich GruttmannAbstract:Abstract In this paper torsion of prismatic bars considering elastic–plastic material behaviour is studied. Based on the presented variational formulation associated isoparametric finite elements are developed. The unknown warping function is approximated using an isoparametric concept. The elastic–plastic stresses are obtained by an Exact Integration of the rate equations. Thus the ultimate torque can be calculated in one single load step. This quantity describes the plastic reserve of a bar subjected to torsion. Furthermore, for linear isotropic hardening no local iterations are necessary to compute the stresses at the Integration points. The numerical results are in very good agreement with available analytical solutions for simple geometric shapes. The arbitrary shaped domains may be simply or multiple connected.
Werner Wagner - One of the best experts on this subject based on the ideXlab platform.
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finite element analysis of saint venant torsion problem with Exact Integration of the elastic plastic constitutive equations
Computer Methods in Applied Mechanics and Engineering, 2001Co-Authors: Werner Wagner, Friedrich GruttmannAbstract:Abstract In this paper torsion of prismatic bars considering elastic–plastic material behaviour is studied. Based on the presented variational formulation associated isoparametric finite elements are developed. The unknown warping function is approximated using an isoparametric concept. The elastic–plastic stresses are obtained by an Exact Integration of the rate equations. Thus the ultimate torque can be calculated in one single load step. This quantity describes the plastic reserve of a bar subjected to torsion. Furthermore, for linear isotropic hardening no local iterations are necessary to compute the stresses at the Integration points. The numerical results are in very good agreement with available analytical solutions for simple geometric shapes. The arbitrary shaped domains may be simply or multiple connected.
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Finite element analysis of Saint–Venant torsion problem with Exact Integration of the elastic–plastic constitutive equations
Computer Methods in Applied Mechanics and Engineering, 2001Co-Authors: Werner Wagner, Friedrich GruttmannAbstract:Abstract In this paper torsion of prismatic bars considering elastic–plastic material behaviour is studied. Based on the presented variational formulation associated isoparametric finite elements are developed. The unknown warping function is approximated using an isoparametric concept. The elastic–plastic stresses are obtained by an Exact Integration of the rate equations. Thus the ultimate torque can be calculated in one single load step. This quantity describes the plastic reserve of a bar subjected to torsion. Furthermore, for linear isotropic hardening no local iterations are necessary to compute the stresses at the Integration points. The numerical results are in very good agreement with available analytical solutions for simple geometric shapes. The arbitrary shaped domains may be simply or multiple connected.
Attila Kossa - One of the best experts on this subject based on the ideXlab platform.
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A new Exact Integration method for the Drucker–Prager elastoplastic model with linear isotropic hardening
International Journal of Solids and Structures, 2012Co-Authors: László Szabó, Attila KossaAbstract:Abstract This paper presents the Exact stress solution of the non-associative Drucker–Prager elastoplastic model governed by linear isotropic hardening rule. The stress Integration is performed under constant strain-rate assumption and the derived formulas are valid in the setting of small strain elastoplasticity theory. Based on the time-continuous stress solution, a complete discretized stress updating algorithm is also presented providing the solutions for the special cases when the initial stress state is located in the apex and when the increment produces a stress path through the apex. Explicit expression for the algorithmically consistent tangent tensor is also derived. In addition, a fully analytical strain solution is also derived for the stress-driven case using constant stress-rate assumption. In order to get a deeper understanding of the features of these solutions, two numerical test examples are also presented.
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a new Exact Integration method for the drucker prager elastoplastic model with linear isotropic hardening
International Journal of Solids and Structures, 2012Co-Authors: László Szabó, Attila KossaAbstract:Abstract This paper presents the Exact stress solution of the non-associative Drucker–Prager elastoplastic model governed by linear isotropic hardening rule. The stress Integration is performed under constant strain-rate assumption and the derived formulas are valid in the setting of small strain elastoplasticity theory. Based on the time-continuous stress solution, a complete discretized stress updating algorithm is also presented providing the solutions for the special cases when the initial stress state is located in the apex and when the increment produces a stress path through the apex. Explicit expression for the algorithmically consistent tangent tensor is also derived. In addition, a fully analytical strain solution is also derived for the stress-driven case using constant stress-rate assumption. In order to get a deeper understanding of the features of these solutions, two numerical test examples are also presented.
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Exact Integration methods of elastic-plastic materials
2009Co-Authors: Attila KossaAbstract:A rugalmas-keplekeny anyagmodellekkel vegzett szamitasok jelentős szerepet toltenek be a gyakorlati alkalmazasokban. A klasszikus elmeletek ervenyessege teljesen elfogadott. A kereskedelmi vegeselemes programrendszerek rendszerint mind tartalmazzak ezen anyagtorvenyeket, melyek kozul az egyik legelterjedtebb a Prandtl–Reuss-fele rugalmas-keplekeny anyagmodell, amellyel a jelen cikk is foglalkozik kombinalt (izotrop es kinematikai) linearis kemenyedes figyelembevetelevel. A vegeselemes szamitasokban jelentkező feszultsegszamitasi eljarasok megkovetelik a sebesseg alaku (novekmenyes) konstitutiv egyenlet integralasat, mely tortenhet numerikus vagy egzakt eljarassal. A vizsgalt modell eseten mar szulettek egzakt megoldasok idealisan keplekeny, linearis kinematikai es linearis izotrop kemenyedes esetere konstans alakvaltozas feltetelezesevel. Ezen eredmenyek felhasznalasaval lehetőseg nyilik a kombinalt kemenyedessel kiterjesztett modell megoldasanak előallitasara, melynek bemutatasaval a jelen cikk foglalkoz...
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Exact Integration of the von Mises elastoplasticity model with combined linear isotropic-kinematic hardening
International Journal of Plasticity, 2009Co-Authors: Attila Kossa, László SzabóAbstract:The main purpose of this work is to present two semi-analytical solutions for the von Mises elastoplasticity model governed by combined linear isotropic-kinematic hardening. The first solution (SOLe) corresponds to strain-driven problems with constant strain rate assumption, whereas the second one (SOLσ) is proposed for stress-driven problems using constant stress rate assumption. The formulas are derived within the small strain theory Besides the new analytical solutions, a new discretized Integration scheme (AMe) based on the time-continuous SOLe is also presented and the corresponding algorithmically consistent tangent tensor is provided. A main advantage of the discretized stress updating algorithm is its accuracy; it renders the Exact solution if constant strain rate is assumed during the strain increment, which is a commonly adopted assumption in the standard finite element calculations. The improved accuracy of the new method (AMe) compared with the well-known radial return method (RRM) is demonstrated by evaluating two simple examples characterized by generic nonlinear strain paths.
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Exact Integration methods of elastic-plastic materials
Építés - Építészettudomány, 2009Co-Authors: Attila KossaAbstract:A rugalmas-képlékeny anyagmodellekkel végzett számítások jelentős szerepet töltenek be a gyakorlati alkalmazásokban. A klasszikus elméletek érvényessége teljesen elfogadott. A kereskedelmi végeselemes programrendszerek rendszerint mind tartalmazzák ezen anyagtörvényeket, melyek közül az egyik legelterjedtebb a Prandtl–Reuss-féle rugalmas-képlékeny anyagmodell, amellyel a jelen cikk is foglalkozik kombinált (izotrop és kinematikai) lineáris keményedés figyelembevételével. A végeselemes számításokban jelentkező feszültségszámítási eljárások megkövetelik a sebesség alakú (növekményes) konstitutív egyenlet integrálását, mely történhet numerikus vagy egzakt eljárással. A vizsgált modell esetén már születtek egzakt megoldások ideálisan képlékeny, lineáris kinematikai és lineáris izotrop keményedés esetére konstans alakváltozás feltételezésével. Ezen eredmények felhasználásával lehetőség nyílik a kombinált keményedéssel kiterjesztett modell megoldásának előállítására, melynek bemutatásával a jelen cikk foglalkozik. Végeredményben a keresett összefüggéseket a nem teljes bétafüggvény felhasználásával implicit alakban kapjuk. Az ismertetett megoldás szerkezete biztosítja az egyszerű implementálási lehetőséget a végeselemes számításokban jelentkező feszültségszámítási eljárásokhoz. Az új módszer hatékonyságát egy tesztpéldán végzett számítás ismerteti.\ud | \ud Elastoplastic constitutive models play a crucial task in engineering problems. The classical models are widely accepted and applied for various cases of elastoplastic calculations. The commercial finite element softwares include these models in general, from which, the Prandtl–Reuss constitutive relation is the most widely used one. This article is concerned with this model extended with combined linear isotropic-kinematic hardening rule. The stress update procedure appearing in finite element calculations requires the Integration of the rate-form constitutive equations. Besides numerical techniques, Exact solutions can also be applied for this task. There are already published Exact solutions for the perfectly plastic, purely kinematic hardening and purely isotropic hardening cases assuming constant strain-rate. Combining these solutions provides the opportunity to obtain Exact solution for the combined hardening case. This paper describes the derivation of the solution corresponding to material governed by combined hardening rule. The final form of the stress solution is given with the help of the incomplete beta function. The numerical efficiency of the proposed solution is demonstrated through a numerical example.\u
Andrea Sportiello - One of the best experts on this subject based on the ideXlab platform.
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Exact Integration of height probabilities in the Abelian Sandpile Model
Journal of Statistical Mechanics: Theory and Experiment, 2012Co-Authors: Sergio Caracciolo, Andrea SportielloAbstract:The height probabilities for the recurrent configurations in the Abelian Sandpile Model on the square lattice have analytic expressions, in terms of multidimensional quadratures. At first, these quantities have been evaluated numerically with high accuracy, and conjectured to be certain cubic rational-coefficient polynomials in 1/pi. Later their values have been determined by different methods. We revert to the direct derivation of these probabilities, by computing analytically the corresponding integrals. Yet another time, we confirm the predictions on the probabilities, and thus, as a corollary, the conjecture on the average height.
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Exact Integration of height probabilities in the abelian sandpile model
Journal of Statistical Mechanics: Theory and Experiment, 2012Co-Authors: Sergio Caracciolo, Andrea SportielloAbstract:The height probabilities for the recurrent configurations in the Abelian Sandpile model on the square lattice have analytic expressions, in terms of multidimensional quadratures. At first, these quantities were evaluated numerically with high accuracy and conjectured to be certain cubic rational-coefficient polynomials in π−1. Later their values were determined by different methods. We revert to the direct derivation of these probabilities, by computing analytically the corresponding integrals. Once again, we confirm the predictions on the probabilities, and thus, as a corollary, the conjecture on the average height, 〈ρ〉 = 17/8.
László Szabó - One of the best experts on this subject based on the ideXlab platform.
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a new Exact Integration method for the drucker prager elastoplastic model with linear isotropic hardening
International Journal of Solids and Structures, 2012Co-Authors: László Szabó, Attila KossaAbstract:Abstract This paper presents the Exact stress solution of the non-associative Drucker–Prager elastoplastic model governed by linear isotropic hardening rule. The stress Integration is performed under constant strain-rate assumption and the derived formulas are valid in the setting of small strain elastoplasticity theory. Based on the time-continuous stress solution, a complete discretized stress updating algorithm is also presented providing the solutions for the special cases when the initial stress state is located in the apex and when the increment produces a stress path through the apex. Explicit expression for the algorithmically consistent tangent tensor is also derived. In addition, a fully analytical strain solution is also derived for the stress-driven case using constant stress-rate assumption. In order to get a deeper understanding of the features of these solutions, two numerical test examples are also presented.
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A new Exact Integration method for the Drucker–Prager elastoplastic model with linear isotropic hardening
International Journal of Solids and Structures, 2012Co-Authors: László Szabó, Attila KossaAbstract:Abstract This paper presents the Exact stress solution of the non-associative Drucker–Prager elastoplastic model governed by linear isotropic hardening rule. The stress Integration is performed under constant strain-rate assumption and the derived formulas are valid in the setting of small strain elastoplasticity theory. Based on the time-continuous stress solution, a complete discretized stress updating algorithm is also presented providing the solutions for the special cases when the initial stress state is located in the apex and when the increment produces a stress path through the apex. Explicit expression for the algorithmically consistent tangent tensor is also derived. In addition, a fully analytical strain solution is also derived for the stress-driven case using constant stress-rate assumption. In order to get a deeper understanding of the features of these solutions, two numerical test examples are also presented.
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Exact Integration of the von Mises elastoplasticity model with combined linear isotropic-kinematic hardening
International Journal of Plasticity, 2009Co-Authors: Attila Kossa, László SzabóAbstract:The main purpose of this work is to present two semi-analytical solutions for the von Mises elastoplasticity model governed by combined linear isotropic-kinematic hardening. The first solution (SOLe) corresponds to strain-driven problems with constant strain rate assumption, whereas the second one (SOLσ) is proposed for stress-driven problems using constant stress rate assumption. The formulas are derived within the small strain theory Besides the new analytical solutions, a new discretized Integration scheme (AMe) based on the time-continuous SOLe is also presented and the corresponding algorithmically consistent tangent tensor is provided. A main advantage of the discretized stress updating algorithm is its accuracy; it renders the Exact solution if constant strain rate is assumed during the strain increment, which is a commonly adopted assumption in the standard finite element calculations. The improved accuracy of the new method (AMe) compared with the well-known radial return method (RRM) is demonstrated by evaluating two simple examples characterized by generic nonlinear strain paths.
